NMR-Directed Design of PreTCR? and pMHC Molecules Implies a Distinct Geometry for preTCR Relative to ??TCR Recognition of pMHC.
Related Articles NMR-Directed Design of PreTCR? and pMHC Molecules Implies a Distinct Geometry for preTCR Relative to ??TCR Recognition of pMHC.
J Biol Chem. 2017 Nov 03;:
Authors: Mallis RJ, Arthanari H, Lang MJ, Reinherz EL, Wagner G
Abstract
The pre-T cell receptor (preTCR) guides early thymocytes through maturation processes within the thymus via interaction with self ligands displayed on thymic epithelial cells. The preTCR is a disulfide-linked heterodimer composed of an invariant preT? (pT?) subunit and a variable ? subunit, the latter of which is incorporated into the mature T cell receptor (TCR) in subsequent developmental progression. This interaction of preTCR with peptide-major histocompatibility complex molecules (pMHC) has recently been shown to drive robust preTCR signaling and thymocyte maturation. While the native sequences of ? are properly folded and are suitable for NMR studies in isolation, a tendency to self-associate rendered binding studies with physiological ligands difficult to interpret. Consequently, in order to structurally define this critical interaction, we have re-engineered the extracellular regions of ?, designated as ?-c1, for prokaryotic production to be used in NMR spectroscopy. Given the large size of the full extracellular domain of class I MHC molecules such as H-Kb, we produced a truncated form termed Kb-t harboring properties favorable for NMR measurements. This system has enabled robust measurement of a preTCR-pMHC interaction directly analogous to that of TCR??-pMHC. Binding surface analysis identified a contact surface comparable in size to that of the TCR??-pMHC but potentially with a rather distinct binding orientation. A tilting of the preTCR? when bound to pMHC ligand recognition surface versus the upright orientation of TCR?? would alter the direction of force application between preTCR and TCR mechanosensors, impacting signal initiation.
PMID: 29101227 [PubMed - as supplied by publisher]
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